This invention relates generally to apparatus for analyzing the rotational movement of a shaft or other rotatable member and in particular to apparatus for analyzing the eccentricity of that rotatable member from the normal rotational axis.
In apparatus having a rotatable member and including computer disk drives and automotive tachometers, for example, there have been shown a number of arrangements for determining the angular velocity and/or the angular position of a rotating member.
Deleris, in U.S. Pat. No. 4,321,580 issued Mar. 23, 1982, teaches a method and apparatus for determining the angular position of a point in rotational motion including a disk coupled to rotate with the rotating part. The disk includes a plurality of alternating teeth and spaces about its periphery. At least one tooth is removed to form a reference mark. A transducer located adjacent the disk produces electrical signals representative of the passage of teeth and spaces past the transducer. From the signals the instantaneous angular position of the reference mark on the rotating part can be determined.
Spalti et al, in U.S. Pat. No. 4,342,025 issued July 27, 1982, disclose an arrangement for determining the angular position of a movable body. A plurality of concentric tracks are movable with the body past individual detecting locations for the respective tracks. The tracks include markings which are distributed along and among the tracks in a predetermined code. Means is provided for detecting the presence of the markings and for transmitting the signals to a common receiver by individual channels associated with respective detecting locations. The detecting signals are transmitted through the channels chronologically and assigned to respective time or space slots of a binary coded, position-indicating output signal by means of a control signal generated at a predetermined instant relative to the sequence of detecting signals.
Mehnert, in U.S. Pat. No. 4,445,087 issued Apr. 24, 1984, teaches a disk member and sensor for determining the instantaneous angular velocity of a rotating shaft. The disk includes a plurality of marks approximately equally distributed along the path swept over by the sensor of the sensing unit. The distance relative to time of two electric signals produced by the sensor is measured with regard to two identified marks in a calibrating run and is stored. During operation, the instantaneous time distance of the sensed signals between marks is measured and the instantaneous velocity is obtained by comparing it with the stored calibrating value.
The prior art has thus shown various arrangements for determining the angular velocity as well as the angular position of a rotatable member. These arrangements have included variations of a disk member attached to the rotatable member. The disk members of the various arrangements have included different means of detecting the angular velocity and angular position such as the plurality of teeth and spaces in U.S. Pat. No. 4,321,580, the plurality of tracks and sensors in U.S. Pat. No. 4,342,025, and the approximately equally distributed marks in U.S. Pat. No. 4,445,087. In spite of these many arrangements for determining angular velocity and angular position of a rotatable member, there has been no known showing of the present laundry appliance including apparatus for analyzing the eccentricity of a rotatable member from it normal axis of rotation.